Polyurethane foams exhibit a wide range of stiffness, hardness, and density. One type of polyurethane foam, flexible polyurethane foam, is especially useful for providing cushioning, support, and comfort for furniture articles. For example, flexible polyurethane foam is often incorporated into furniture comfort articles, such as cushions, padding, mattresses, topper pads, and pillows, as well as furniture support articles, such as sofas, love seats, and chairs.
Flexible polyurethane foams are typically flammable, especially when subjected to repeated compression and bending, but can be formulated to resist small open flame ignition sources. The repeated compression and bending often compromises the cellular structure of flexible polyurethane foams. This phenomenon is generally referred to as flex fatigue. Since flexible polyurethane foams are repeatedly subjected to compression and bending and thus, over time, experience flex fatigue when used in furniture comfort and support articles, United States federal and state regulations currently proscribe flammability limits for flexible polyurethane foams. One such federal regulation, 49 C.F.R. § 571.302-Standard No. 302, specifies requirements, test procedures, and equipment for testing the flammability of interior materials, e.g. flexible polyurethane foams, in vehicles such as passenger cars, multipurpose passenger vehicles, trucks, and buses. One such state regulation, State of California Technical Bulletin 117, specifies requirements, test procedures, and equipment for testing flame retardance of resilient filling materials, e.g. flexible polyurethane foams, in upholstered furniture.
Various approaches for producing flexible polyurethane foams exhibiting flame retardance and flexibility are known in the art. Many existing flexible polyurethane foams exhibiting flame retardance rely on inclusion of conventional flame retardant additives. For example, flame retardant additives including minerals, such as aluminum trihydrate; salts, such as hydroxymethyl phosphonium salts; phosphorous compounds; phosphated esters; and halocarbons or other halogenated compounds, such as those including bromine and/or chlorine; may be included. However, there are disadvantages associated with inclusion of conventional flame retardant additives flexible polyurethane foams. More specifically, conventional flame retardant additives are expensive, can complicate the production/formation of flexible polyurethane foams, and can negatively impact the physical properties of flexible polyurethane foams formed therewith.